1. Field of the Invention
The present invention relates, in general, to methods and apparatus for testing the structural integrity of building materials such as exterior siding, sheathing, and framing on buildings, such as might be found, for example, underneath synthetic stucco and stucco.
2. Description of the Prior Art
There are three major types of stucco-type exteriors for buildings, namely, "job-mixed" stucco, "mill-mixed" stucco, and synthetic stucco.
So-called job-mixed or "traditional" stucco is a mixture of portland cement, hydrate lime, aggregate (usually sand), and water, mixed in a manner and in proportions well-known to those skilled in the art. This stucco mixture is applied to a metal lath base attached to the outside of a substrate on the exterior of a building, and the stucco covers and is embedded within the lath. The substrate should be or have a moisture barrier in order to keep water drainage from entering the underlying substrate structure. A first or "scratch" coating of the stucco mixture is applied to embed the lath and then a second coating of the stucco mixture is applied to bring the stucco thickness to approximately 0.75 inch (1.9 cm), the minimum acceptable standard. Additives for the stucco mixture are available to provide a third and final coating with a variety of textures and colors. Also, elastomeric or acrylic coatings may be used for the final coat.
So-called mill-mixed stucco consists of the same basic materials as does job-mixed stucco, except that some manufacturers add chemical plasticizers to enhance the workability of the stucco and also may add fibers to provide additional strength to the finished stucco. The lath system for mill-mixed stucco is basically the same as for job-mixed stucco, but accessory trim pieces will typically be designed for the required depth of the applied mill-mixed stucco. A texture coat is often applied as a second coat to the mill-mixed stucco, but texture and color can also be provided by the application of a third stucco coat, as with the job-mixed stucco.
Synthetic stucco, otherwise known an Exterior Insulation and Finish System ("EIFS"), is a barrier-type cladding system that relies entirely on the exterior surface to keep moisture out of the cladding. Because there is no internal drainage system, the design and quality of workmanship is an important component in ensuring a water-tight finish. There are two variants of EIFS synthetic stucco systems, namely, EIFS Polymer Based and EIFS Polymer Modified.
EIFS Polymer Based ("EIFS PB") stucco systems, commonly referred to as the "soft system", is more soft and flexible due to a higher resin content. The system is adhesively and/or mechanically attached to the substrate, and has been commonly used for the last ten years in the Mid-South region of the United States. The expanded polystyrene ("EPS") base of the EIFS PB stucco system is a minimum of 0.75 inch (1.9 cm.) thick, and the EPS board is usually attached to the structural sheathing using a polymer-modified cement or an emulsion-type cement that does not attack the EPS board. In some instances, large (usually plastic) washers are nailed or screwed through the EPS board to provide additional or primary attachment of the EPS board to the substrate or frame. After allowing time to cure, usually 24 hours, fiberglass mesh is embedded into a layer of polymer-modified cement troweled over the EPS board. This troweled cement layer must dry before the finish coat can be applied (usually, another 24 hours). The finish coat is, most often, an elastomeric or acrylic containing color and an aggregate of the type required to obtain a desired texture. The EIFS PB synthetic stucco system is a single barrier, water exclusion, system. Most manufacturers have tested their lamina for water penetration, and most are water tight. However, a water vapor can pass through, thereby allowing the system to ventilate. Because this system is a single-barrier system, when or if water infiltrates through an unsealed area, the water is trapped until it vaporizes. If this condition persists, and the source of water intrusion is not stopped, then structural damage can occur. In response to the water infiltration problems with the EIFS PB synthetic stucco system, most manufacturers have designed a moisture management system ("PBMM"), whose purpose is to release any trapped water down a drainage plane between the sheathing and the EPS board.
EIFS Polymer Modified synthetic stucco systems, commonly referred to as the "hard system", is a cross from mill-mixed stucco and the EIFS PB moisture management system. The EIFS Polymer Modified synthetic stucco system does not provide a drainage plane and the wall has a hard base and finish coat. This system can often be installed over EPS board or an extruded polystyrene sheet.
The sheathing substrate most commonly used behind BIFS systems are exterior gypsum board, oriented strand board ("OSB"), and 0.5 inch (1.27 cm) CDX plywood. Other substrates are approved but not often used.
Because of excessive water intrusion and retention within its barriers, EIFS synthetic stucco systems have produced internal wall damage and rot to the underlying dwelling structure. There is uncertainty among those skilled in the art as to whether these problems stem from improper installation of the EIFS product or instead from a defect relating to or inherent in the product itself. Some manufacturers of EIFS have changed their product specifications in an attempt to reduce these problems.
As installed EIFS ages, excessive water intrusion may result from improper maintenance of the necessary seals around the points of water entry (e.g., window frames, doors, etc.) and from punctures in the exterior of the EIFS. Subsequent home improvement projects and repair of punctures in the EIFS exterior by uninformed workmen may result in inadequate seals that lead to excessive water intrusion and resulting rotting of the underlying sheathing substrate.
In an EIFS-covered wall, excessive water retention and internal wall damage may have no visible signs and may be undetectable by typically knowledgeable persons. Similarly, it is difficult to evaluate dwellings for suspected termite damage behind an EIFS synthetic stucco exterior. Prior art methods of testing for sheathing rot damage under an EIFS-covered wall required drilling and cutting of the EIFS covering so that moisture probes could be inserted to test for moisture, or else the EIFS covering would be partially or completely removed for inspection, and removal of the EIFS exterior is believed to be the only known prior art method of evaluating the underlying wood structures for termite damage. A typical and well-known moisture probe often used in such testing is the Delmhorst moisture meter model BD-8 or BD-9 using model 21E moisture probe electrodes. Such prior art methods of testing were intrusive and destructive of the EIFS covering, often resulting in great unnecessary expense to the dwelling's owner.
Additionally, prior art testing using moisture probes is successful in identifying trapped moisture under the EIFS covering, but did not directly test the structural integrity of the underlying substrate for rot. The focus of the prior art testing methods was to identify the presence of rot-causing moisture so that the source of the moisture could be addressed. However, in those situations where moisture had been present in the past but was no longer present, the prior art methods of testing could indicate satisfactory EIFS conditions because of the lack of moisture when, in fact, prior significant rot damage to the underlying substrate had occurred.
Therefore, a method and apparatus for testing the structural integrity of building materials such as a building's sheathing and framing is needed that can test for rotting and termite-damaged substrate sheathing such as might be found behind synthetic stucco without requiring removal of synthetic stucco or stucco outer layers.